Morphology of the perivascular regions of the rat neural lobe in relation to hormone release.

Neural lobes of rats subjected to dehydration by drinking 2% saline for four days were examined electron microscopically and compared to untreated controls. The ultrastructure of the blood vessels and the tissues surrounding them were examined and it was found that, although few exocytotic figures could be seen in either group of animals, a significantly larger (P smaller than 0.01) number os small vesicles were found in nerve endings adjacent to the perivascular space in the saline treated group when compared to nerve endings not closely associated with blood vessels. No differences were found in the control group of animals, which supports the suggestion that the vesicles could arise from a membrane recapture process.